我正在尝试在 phpfog 上实现 yii 框架附带的一个小默认应用程序。我已经按照使用 GIT 的说明安装了它。现在，当我尝试运行它时，我收到了这个错误（如下）。我已经检查以确保该目录是可写的并且所调用的目录确实存在。我被困住了，接下来我该怎么办？
Application runtime path /var/fog/apps/app35423/austintxous.phpfogapp.com/demos/emp/protected/runtime" is not valid.
Please make sure it is a directory writable by the Web server process.
259 return $this->_runtimePath;
260 }
261 }
262
263 /**
264 * Sets the directory that stores runtime files.
265 * @param string $path the directory that stores runtime files.
266 * @throws CException if the directory does not exist or is not writable
267 */
268 public function setRuntimePath($path)
269 {
270 if(($runtimePath=realpath($path))===false || !is_dir($runtimePath) ||
!is_writable($runtimePath))
271 throw new CException(Yii::t('yii','Application runtime path "{path}" is
not valid. Please make sure it is a directory writable by the Web server process.',
272 array('{path}'=>$path)));
273 $this->_runtimePath=$runtimePath;
274 }
275
276 /**
277 * Returns the root directory that holds all third-party extensions.
278 * @return string the directory that contains all extensions. Defaults to the
'extensions' directory under 'protected'.
279 */
280 public function getExtensionPath()
281 {
282 return Yii::getPathOfAlias('ext');
283 }